Suppose a group of students come to school on the anniversary of the Columbine school shooting wearing white shirts with red marks on them as a way to represent those students who have died in school shootings over the years. The school administration believes this is distracting to other students and orders the students to go home and change. The students refuse, citing which previous incident?

the $1960$s protests of the Vietnam War in which students were permitted to wear black armbands.

the Supreme Courts decision on United States v$.$ OBrien

the precedent set by the Supreme Court regarding libel and slander requirements

the flag$-$burning by Gregory Lee Johnson and the Courts removal of his conviction